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Let’s talk gas tank size and batteries!


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Let’s talk gas tank size and Batteries!

 

So I think I had a reoccurring issue rear its head again and maybe did a bone head thing. I apologize for the long read, but I think all this info is pertinent.

 

So first a little background:

 

When we got our boat in 2014 we had several problems with batteries dying and stereo battery dying frequently. A few new batteries and a battery tender seemed to rectify the problem, and I started religiously charging the batteries nightly when we are out (we currently don’t have a dock so we have to pull out at the end of the day). I mainly did this because we would do a lot of sitting and listening to music that I thought would suck the stereo battery dry.

 

Fast forward to this weekend. We spent the majority of our time either running around and surfing in the mornings or anchored in large groups with the boat off. I was lax since we weren’t doing any floating and listening to music, so I didn’t plug her in on Saturday night or Sunday night. By day 3 one of my amps was going into protect mode due to low voltage, so I turned the stereo off and figured it was just from not charging the battery (my mistake). Well to compound the situation I had my lovely co captain fill up at the marina on Sunday (my oldest had strep and I had to take her to the immediate care center) and they did one surf set of about 30 minutes before coming in. 

 

Well they didn’t tell me that they only put 15 gallons in and didn’t fill her all the way up. So we went out surfing like we normally do yesterday morning (several people each doing a set) and some running around by the time I get back in the driver seat we are just over a 1/4 of a tank left. I told my co captain that we must have burned a lot more gas than we normally do and that we needed to go get some, and this is when she told me they didn’t actually fill up the day before. I said we definitely need to run over to the marina to fill up again because we were planning on maybe doing another set that evening. As we had a 1/4 tank I figured we had plenty of gas for just putzing around to the marina just didn’t want to get any lower. 

 

Well while we are waiting in line at the marina to get gas the boat idles rough and then dies. I try restarting her and she’s really struggling to crank. I figure it was just my bonehead move of not putting the batteries on charge and that my main starter battery isn’t strong enough to start the boat either at this point.

 

So we tie up and eat lunch while we wait for some family members to come give us a tow. We wander into the marina to get ice cream and I realize they had batteries there. Knowing that my stereo battery is 3 years old now, I went ahead and bought one thinking it would get us through the rest of the day (or at least avoid a tow). I put the battery in and she doesn’t start at first (I figure she might be a bit flooded from trying to crank her earlier). On the third try she turns over and starts just like normal. I figure before untying front the end of the marina to go get gas, that we would let her idle for a second to make sure that everything was ok. Sure enough after about two minutes she dies again. Now I’m wondering about gas and maybe a 1/4 a tank isn’t really a 1/4 or a tank (I can’t remember ever getting her this low). 

 

So we swim the boat over to the pumps and put 20 gallons in her. Again after a couple of cranks she turns right over. Drove her around a little bit and no more problems for the rest of the afternoon. Once we pulled her, we topped her off and she only took another 20 gallons (I think this is key to one of my questions).

 

I know the above is a wall of text but I wanted to make sure I included all info that could be pertinent. So this leads me to a few questions that may or may not be related:

 

1. So obviously I believe I was out of gas, however if you look between the marina fill up after it died and the gas station fill up we only put 40 gallons in before she was full. All the specs I’ve found say that the table should be 46 gallons. So I should have still had 6 gallons in the tank (about an 1/8 of a tank). Is that fuel tank capacity wrong? Is the tank not designed in a way where it can use the last 6 gallons?

2. As far as I know the boat still has the original alternator on it. Is there a chance my alternator needs to be replaced? Could it just be charging at a low enough output that it can generally run the boat, but my nightly charging are actually charging all the batteries? The alternator should charge both batteries while on the “all” setting of the battery switch correct? I generally run the boat with the all setting, and then switch to battery #2 when floating and listening to music. (The amps are only wired to battery #2). Is the alternator supposed to be strong enough to charge these batteries?

3. Do I have the right type of batteries? The two original batteries I started the weekend with were both 24 series marine batteries with 600 and 800 mca respectively. I replaced the older 24 series 800 mca battery with a new 27 series 750 mca battery. These are standard batteries you would get from Walmart/autozone. One is a Walmart brand and the 27 series I bought yesterday is an interstate. I have friends that have pontoons and wakeboats and I feel like they don’t have near the problems with batteries like I do. One of them I know only charges there batteries over the winter as the boat is either in a dock slip or in storage with now power access during the summer. Also I think there are tons of people on here that also leave their boats on the lift or in the dock for the weekend and they don’t have problems with stereo batteries losing charge? My stereo system isn’t insane (2 revs 8’s, 6 kicker in boats, a sub, a syn 4 amp to drive wetsounds , and a kicker kmx 800.5 amp to drive sub and in boats), so I feel like I’m having too many problems if I don’t charge the batteries? Maybe I’m just misguided here....

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The way the tanks are shaped 6 gallons doesn't add up to much depth.  It seems they could do a little better on the gauges though.  I think you have some electrical issues, does not sound normal to me at all.  I have two marine starting batteries and have never charged them during boating season although we don't listen to that much music. 

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Are you sure your battery switch is wired  correctly?  What is the dash voltage meter showing?

I have an ACR, stereo about your size, float and listen, and  never put the batteries on a charger.  Something in your system is screwed up.

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I never thought to check the switch wiring as it has always seemed to work. I do know that when its on "1" it only runs from battery 1 and when its on "2" it only runs from battery two. can it be wired where it won't charge both batteries? As far as the dash volt meter its 12+ when starting the boat and 14+ when running under load.

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Maybe your starting battery is bad?  I think I followed your narrative correctly and you start the boat with the switch on both batteries.  It could be sucking current from your new stereo battery.

Your alternator seems to be doing its job.  I would try to start with the batteries disconnected to see if the starting battery is good.  I'm an real fan of ACRs.  Put em in and forget them.  If a battery starts to go bad it'll show itself.

Just saw Ndawg12's post and agree.  If the bow is weighted then you may not have gas at the back of the tank where the pickup is.  Gauge may still show there is plenty of gas.

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First step would be to make sure ALL of your battery (positive and negative) connections are CLEAN and TIGHT.  This includes the wire from alternator from starter, the wire from starter to switch/breaker (depending how wired) and wires from switch to battery.  Don't forget your grounds.  IIRC the ground connection terminates on your block behind the back seat (kinda over the trans).  Wouldn't be a bad idea to double check to see if that ground wire goes to bare metal or painted metal (and if painted, sand bare/reconnect/put some dielectric grease over it to prevent corrosion and rusting).

Once you have done all that, run the boat and check voltage.  What do the gauges say?  What does your multimeter say voltage is at the batteries, at the starter, etc?  

I had a similar issue to you on a 2006 boat, and was advised by indmar at the time that in 2006 Malibu cheaped out with thinner gauge wire from starter to batteries, and that if there were any other issue (slightly aged batteries, unclean contacts, you name it) that you'd get a crank but no fire condition because the ecm would determine that there wasn't enough voltage to fire.  I ended up replacing the wire from the starter (positive) and block (ground) with beefier wire and the problem never came back.  

 

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On 9/5/2018 at 12:42 PM, DaDeuce said:

 

1. So obviously I believe I was out of gas, however if you look between the marina fill up after it died and the gas station fill up we only put 40 gallons in before she was full. All the specs I’ve found say that the table should be 46 gallons. So I should have still had 6 gallons in the tank (about an 1/8 of a tank). Is that fuel tank capacity wrong? Is the tank not designed in a way where it can use the last 6 gallons?

 

since the majority of posters tackled the battery issue I will provide details on you the tank and gauge

  1. MOST IMPORTANT... As preached to me when I was flying.. a gas gauge is good for one thing, to let you know when tanks are full. Always fill up before outings no matter what gauge states.
    1. The attitude of the boat will display different levels of fuel, it is only accurate when level and not moving.
  2. While the tank holds 46 gallons, not all the fuel is accessible to the pump.
    1. The pump has a filter on the bottom of it and must be fully submerged to pump fuel.
      1. Even though there is still fuel in your tank, the pump can't access it due to the filter.
    2. Having no fuel over the intake filter can also burn a pump up, as the pump is cooled by the fuel flowing through it (early to mid mastercrafts are known for this, as most vehicles... I only know of the mastercrafts as an example as a friend that owns one learned this lesson and it was a common write up).

One thing on the battery issue that was not fully stated from you was how long you turned the motor over to try and start. If you are turning motor over for an excessive time frame, the starter will get hot (https://www.knowyourparts.com/technical-resources/starting-and-charging/starter-will-not-crank-when-hot-heat-soak). This could also be caused by heat in the compartment as well.

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20 minutes ago, kerpluxal said:
  1. MOST IMPORTANT... As preached to me when I was flying.. a gas gauge is good for one thing, to let you know when tanks are full. Always fill up before outings no matter what gauge states.

This.  I've never understood not filling the tanks, especially if you're surfing...it's more "free" ballast anyway and the fuel doesn't go bad.

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Totally agree on filling tanks. It really was the first time the better half was out on the boat without me. She figured that she would save some $ since there’s a gas station not too far from our cabin that we normally fill up at everyday, but alas forgot to tell me!

I’ll definitely check the switch wiring and the gauge of wire from the block back.

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At this point, I would worry less about battery type, brand or size, but rather is my alternator charging properly and is that charge reaching the batteries. Low batteries at rest is almost a non-issue when the engine is running, IF the alternator is doing its job. 

If the boat did run out of gas, this would not effect the speed at which the engine turns over. The engine would spin over as normal, just not fire it, it would just rrrrrrrr, rrrrrrrr, rrrrrrr and so on. Low battery voltage on the main battery would lead to a slow or sluggish cranking battery

This no brings me to the next point. What type of main battery switch do you have and how are you using it. With a dual bank system, your main cranking battery should never be run down at anchor, unless you choose to do so.  

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3 minutes ago, MLA said:

At this point, I would worry less about battery type, brand or size, but rather is my alternator charging properly and is that charge reaching the batteries. Low batteries at rest is almost a non-issue when the engine is running, IF the alternator is doing its job. 

If the boat did run out of gas, this would not effect the speed at which the engine turns over. The engine would spin over as normal, just not fire it, it would just rrrrrrrr, rrrrrrrr, rrrrrrr and so on. Low battery voltage on the main battery would lead to a slow or sluggish cranking battery

This no brings me to the next point. What type of main battery switch do you have and how are you using it. With a dual bank system, your main cranking battery should never be run down at anchor, unless you choose to do so.  

This x100000

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On 9/5/2018 at 12:42 PM, DaDeuce said:

2. As far as I know the boat still has the original alternator on it. Is there a chance my alternator needs to be replaced? Could it just be charging at a low enough output that it can generally run the boat, but my nightly charging are actually charging all the batteries? The alternator should charge both batteries while on the “all” setting of the battery switch correct? I generally run the boat with the all setting, and then switch to battery #2 when floating and listening to music. (The amps are only wired to battery #2). Is the alternator supposed to be strong enough to charge these batteries?

As @shawndoggy states... use a multi reader at each point (alternator, battery, starter) to ensure all locations are receiving the same voltage, any difference here will show an issue with the wiring. Reading you 2nd point again, I noticed something stated that @minnmarker stated and elaborate on it:

If battery one is fully charged and battery two is weak and you put the selector on both, then Battery one will drain to battery two until both are equalized. This can cause not enough amperage to start the boat as now battery 1 has reduced its charge to compensate for battery 2.  I try to use battery one as my starter battery and battery two for those rare moments that I am possibly at beach or filling and listening to radio. When I am done for the day, I switch to both on my way to back to charge both batteries.

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I charge the battery before every outing.

I fill tha gas tank before every outing....

After living on this planet for 60 plus years some folks call this wisdom...

Others call it learnings from the school of hard knocks.

After all these years it is a little of both...  what works works, what doesn’t avoid......

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